The present invention relates to particulate or granular medicated animal feed supplements and methods for making the same.
Antibiotics, such as tetracyclines, are used as growth promoters and feed efficiency promoters in animals such as livestock, and for therapeutic and prophylactic disease control in animals such as poultry and livestock, domesticated pets, and so forth. Such antibiotics are typically formulated in an animal feed premix or animal feed supplement containing the antibiotic and an edible carrier. These premixes or animal feed supplements may then be mixed with a sufficient quantity of an appropriate animal feed to provide a final animal feed formulation having the desired level of active compound in the feed.
One problem associated with animal feed medication pertains to the loss of finely divided antibiotics through dusting and electrostatic adhesion of finely divided particles, which may cause a lack of uniformity in drug concentrations in the final feed from batch to batch. Dust particles that adhere to feed mills or other feed processing equipment or that may be carried away in dust collection system may contain significant quantities of the active ingredient. This may cause the feed mixtures to have a lower concentration of the medicament desired. Dust adherent to the feed processing equipment and dust collected in a dust collection that is recycled in subsequent batches may cause the feed mixtures produced in later batches to have a higher concentration of the active ingredient than desired, or may cause carry over of the drug to feed batches which are not intended to contain the drug.
Several attempts have been made to overcome the problem of dust formation in animal feed premixes and supplements. For example, it is known to add oil to reduce the dust and electrostatic adhesion in animal feed supplements. In U.S. Pat. No. 4,211,781, there is taught a process for preparing a substantially dustless carbadox animal feed premix by admixing carbadox with a non-toxic oil and an edible carrier. In U.S. Pat. No. 3,696,189, it is taught to coat the antibiotic particles of an animal feed supplement an oil to stabilize the antibiotic against the deleterious effects of moisture or other materials contained in the animal feed supplement. It is also known to add oil as a pharmaceutically and nutritionally acceptable carrier or diluent for animal feed supplements.
Another attempt to overcome the problem of feed batch cross contamination is taught in U.S. Pat. No. 4,447,421, directed to a process for making particulated animal feed premixes by combining the drug with a compressible carrier, followed by blending the mixture, compressing the mixture, and granulating the composition. Although this process has been somewhat successful in reducing dusting, it would be desirable to reduce dusting further. Attempts have been made to do so through the addition of oil, however, it has been found that the addition of oil causes a loss of structural integrity of such compressed formulations and causes a separation of the drug from the carrier.
It would be desirable to provide an animal feed premix or animal feed supplement which can be prepared directly from a fermentation product without isolating or purifying the antibiotic from the fermentation solids, and which can be prepared in a granular or particulate form without a compression or compaction step, and which does not lose its structural properties upon admixture with oil.
FIG. 4 is a diagrammatic illustration of a prior art method of manufacturing oxytetracycline feed supplements. Oxytetracycline may be formed by a fermentation process, for example, as described in U.S. Pat. No. 2,516,080. The fermentation product comprising the fermentation solids (mycelium) and fermentation liquid are made acidic and the fermentation solids removed from the fermentation broth. The removed solids are discarded and the oxytetracycline may be purified from the liquid by a number of methods. The purified oxytetracycline crystals are typically micron sized (around 600 mesh) and are may be used to form a standardized feed additive by the addition of mineral products, wax, roughage, etc. The final product is a finely divided meal (powder) and is subject to the electrostatic and dusting problems as described above. There is not currently available in the art an animal feed supplement comprising a granular formulation having a relatively large particle size. Therefore, it would also be desirable to provide an oxytetracycline formulation that is granular in nature and of relatively large particle size suitable for use in the veterinary and animal husbandry arts.
The present invention thus provides medicated animal feed additives in a solid particulate or granular form having improved resistance to powdering and good fracture toughness. The animal feed additive according to the present invention does not require a compression or pressing step to achieve its solid structural form. A dust suppression agent (such as an oil, fat, wax, glyceride, or the like) may optionally be added to bind dust without loss of the structural integrity of the particles. The present invention also provides a method of producing animal feed compositions.
In a further embodiment, there are provided particulate compositions, and methods for making the same, comprising oxytetracycline or chlortetracycline prepared from a fermentation medium and fortified by the addition of pure or semi-pure oxytetracycline or chlortetracycline thereto. As used herein, the term pure or semi-pure oxytetracycline is intended to encompass, the free base, salts of oxytetracycline acceptable for pharmaceutical or veterinary use including acid addition salts, and metal complexes of oxytetracycline and salts thereof, including oxytetracycline calcium complexes. The term pure or semi-pure chlortetracycline is intended to encompass, the free base, salts of chlortetracycline acceptable for pharmaceutical or veterinary use including acid addition salts, and metal complexes of chlortetracycline and salts thereof, including chlortetracycline calcium complexes.
In still a further embodiment, there are provided particulate compositions, and methods for making the same, comprising chlortetracycline prepared from a fermentation medium and fortified by the addition of pure or semi-pure chlortetracycline thereto. In an embodiment, the fermentation medium may further comprise a fermentation residue that has had the antibiotic separated therefrom.
In additional embodiments, the present invention also relates to a method of combating microbial infection in animals comprising orally administering to said animals a prophylactic or therapeutic amount of an animal comestible composition comprising a medicated feed supplement according to the present invention. In yet a further embodiment, the present invention relates to a method for promoting animal growth.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as claimed. The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate an embodiment of the invention and together with the general description, serve to explain the principles of the invention.